With this, the opposition Bharatiya Janata Party`s strength in the 68-member state Assembly has risen to 27. The ruling Congress is having a thin majority with 36 members, though it has roped in five Independents.
Speaker Brij Bihari Lal Butail administered the oath of office and secrecy to Thakur.

The Sujanpur Assembly seat fell vacant after Independent legislator Rajinder Rana resigned to contest the Lok Sabha election as a Congress candidate.
In the by-poll, Thakur defeated Congress candidate and Rana`s wife Anita by a slender margin of 538 votes.

"I had earlier contested elections on the BJP and the Congress tickets and even as an Independent. But this my first success. I will try to strengthen the BJP," Thakur told reporters here after taking oath.